Function

type
String|Object
the attribute type
options
Object
a hash of options
returns
Attribute

attr defines an attribute on a Model. By default, attributes are passed through as-is, however you can specify an optional type to have the value automatically transformed. Ember Data ships with four basic transform types: string, number, boolean and date. You can define your own transforms by subclassing Transform.

Note that you cannot use attr to define an attribute of id.

attr takes an optional hash as a second parameter, currently supported options are:

  • defaultValue: Pass a string or a function to be called to set the attribute to a default value if and only if the key is absent from the payload response.

Example

app/models/user.js
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import Model, { attr } from '@ember-data/model';

export default Model.extend({
  username: attr('string'),
  email: attr('string'),
  verified: attr('boolean', { defaultValue: false })
});

Default value can also be a function. This is useful it you want to return a new object for each attribute.

app/models/user.js
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import Model, { attr } from '@ember-data/model';

export default Model.extend({
  username: attr('string'),
  email: attr('string'),
  settings: attr({
    defaultValue() {
      return {};
    }
  })
});

The options hash is passed as second argument to a transforms' serialize and deserialize method. This allows to configure a transformation and adapt the corresponding value, based on the config:

app/models/post.js
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import Model, { attr } from '@ember-data/model';

export default Model.extend({
  text: attr('text', {
    uppercase: true
  })
});
app/transforms/text.js
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import Transform from '@ember-data/serializer/transform';

export default Transform.extend({
  serialize(value, options) {
    if (options.uppercase) {
      return value.toUpperCase();
    }

    return value;
  },

  deserialize(value) {
    return value;
  }
})